Decorative mouth guard



FIG. 1 is a top perspective view of a decorative mouth guard showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a rear side view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines shown in the drawings represent portions of the decorative design that form no part of the claimed design. 

CLAIM The ornamental design for a decorative mouth guard, as shown and described. 